The present invention relates to a fuel cooling apparatus of an outboard motor.
An outboard motor is generally provided with a water-cooled type engine which is cooled by utilizing seawater or like and with equipments for a fuel system arranged at the periphery thereof.
FIG. 10 is a block diagram showing a cooling system and a fuel system in a general outboard motor. As shown in FIG. 10, a seawater is introduced to an engine 2 through an operation of a water pump 1.
A portion of the introduced cooling water is branched into two flows before reaching the engine 2, one being introduced to the engine 2 and the other being introduced to the fuel system. The cooling water introduced to the engine 2 is discharged after being introduced to a water jacket 3, for example, formed in a cylinder block 2a or like so as to cool the engine 2. In this case, a thermostat 4 for preventing the engine 2 from being excessively cooled is provided at an outlet portion of the water jacket 3.
On the other hand, a fuel in a fuel tank, not shown, is fed under pressure to a vapor separator 8 by means of a low pressure fuel hose 7L through an operation of a low pressure fuel pump 6L after being filtered by a low pressure fuel filter 5L. The fuel in the vapor separator 8 is fed under pressure to a high pressure fuel filter 5H through the operation of a high pressure fuel pump 6H disposed in the vapor separator 8, fed to a delivery pipe 9 by means of a high pressure fuel hose 7Ha after being filtered and then injected to a suction port, not shown, by a fuel injector 10 provided for the delivery pipe 9.
Further, a branch pipe 11 is provided at a middle portion of the high pressure fuel hose 7Ha extending to the delivery pipe 9 from the high pressure fuel filter 5H. Further, a high pressure return fuel hose 7Hb extending to the vapor separator 8 is connected to a branch portion 11a of the branch pipe 11 and is connected to a pressure regulator 12 disposed in the vapor separator 8.
In this case, since the engine 2 of the outboard motor can not be excessively cooled because an oil temperature should be kept at a predetermined temperature, and accordingly, a temperature of an atmosphere in an engine cover is increased, so that the fuel in the fuel system generates a vapor, and a vapor generation is reduced by forming a water jacket 13 in the vapor separator 8 so as to introduce a portion of the engine cooling water in the water jacket 13 to thereby cool the fuel.
However, when the water jacket is formed in the vapor separator in order to cool the fuel, a structure of the vapor separator becomes completed, and an outer shape of the vapor separator becomes large, thus being inconvenient for the compact structure of an outboard motor.
The present invention has been made by taking the matters mentioned above into consideration, and an object of the present invention is to provide a fuel cooling apparatus of an outboard motor having a compact structure and achieving an effective operational functions.
This and other objects can be achieved according to the present invention by providing a fuel cooling apparatus of an outboard motor which is provided with a water-cooled engine having a crank shaft arranged substantially in a vertical direction and in which a fuel is supplied to the engine through a fuel injector after temporarily introducing the fuel to a vapor separator, wherein a high pressure fuel pump is arranged in the vapor separator so as to feed the fuel under pressure to the fuel injector, a pressure regulator is arranged in the vapor separator so as to reduce a pressure of a return fuel, a fuel cooler having a fuel passage and a cooling water passage arranged side by side in parallel to each other is arranged on an upstream side of the pressure regulator, and cooling water for cooling the engine is introduced to the cooling water passage so as to cool the fuel in the fuel passage.
In preferred embodiments in the above aspect of the present invention, the engine is provided, on a side surface thereof, with a suction manifold constituting a suction device and the fuel cooler is mounted to the suction manifold through at least one bracket. The fuel cooler is arranged in a space between a mounting portion of the suction manifold and a delivery pipe to which the fuel injector is mounted.
The cooling water for cooling the engine is branched upstream of the engine side and one of the branched cooling water portions is introduced to the fuel cooler. The fuel cooler is extrusion molded or draw molded from an aluminum material so as to integrally form the fuel passage and the cooling water passage.
As mentioned above, according to the fuel cooling apparatus of the outboard motor of the present invention, the outboard motor can be made compact. It is possible to reduce the number of the assembling steps due to the modulation, reduce the weight and make the shape of the fuel cooling apparatus compact. Furthermore, the cooling effects of the fuel can be enhanced.
The structure and the shape of the cooling apparatus can be made simple. The dead space in the engine can be effectively utilized.
The nature and further characteristic features of the present invention will be made more clear from the following descriptions with reference to the accompanying drawings.